I'd check eBay and see what they have sold for on their site. I hate using it, but for big ticket items eBay has always yielded better prices than Craigslist. I'm not in a big market (Portland, OR), so if you're in a bigger town (like LA), you might do well with Craigslist after pricing from eBay.
It's funny that you want to sell you nMP for a 5K iMac. I am actually torn between the two. I was looking at a nMP with your specs and am tempted to save money and get the 5K iMac. I shoot 4K but edit in 1080p for the time being. It will only be a matter of time before I can switch to 4K, but I need a better Mac than I currently have at the moment. Message me when you get a price and I might be interested.

It's important to understand the application(s) you run. If they have a consistent, steady, high CPU utilization you're better off with the Mac Pro.

I'll tell you why: The 4790K processor, while impressive for the most part, isn't "industrial strength." That is, unlike the socket 2011 processors, it will throttle when under load for a relatively short period of time. Here's what I mean:

I recently built 3 machines for a specific live video streaming application (it only runs on Windows, so I'm using Windows 8.1 on them). This app puts a constant load on the CPU with occasional peaks. A 30% faster CPU means I can literally do 30% more on it - higher resolutions, more remote cameras, more recordings or outputs, etc.

The 8-core i7 5960x ran about 30,000 on 64-bit Geekbench; the 6-core i7 5820K was around 22,500. The 4-core i7 4790K ran around 16,500 - maybe even 17,000. All processors were running at 4GHz. Then, when I ran the constant-loop Geekbench stress test mode (which I believe only runs in 32-bit mode), the scores were about 29,000 22,000 and 15,500 respectively (due to the 32-bit mode). HOWEVER, after about 5-10 minutes (maybe even less) the 4790K throttled down to 13,500 and wouldn't go any higher. The 6 and 8 core processors maintained their speed for hours on end.

I was originally excited about the prospect of running the "high-value" 4790K processor, but after realizing it barely ran faster than my $600 i7 laptop under load (which can't always handle video streaming without stuttering, even though GB stress test remains steady on it at 11,500 for 30+ minutes), I took it back and kept the 6 and 8 core machines. And I've had zero stuttering problems with them.

It's important to understand the application(s) you run. If they have a consistent, steady, high CPU utilization you're better off with the Mac Pro.

I'll tell you why: The 4790K processor, while impressive for the most part, isn't "industrial strength." That is, unlike the socket 2011 processors, it will throttle when under load for a relatively short period of time. Here's what I mean:

I recently built 3 machines for a specific live video streaming application (it only runs on Windows, so I'm using Windows 8.1 on them). This app puts a constant load on the CPU with occasional peaks. A 30% faster CPU means I can literally do 30% more on it - higher resolutions, more remote cameras, more recordings or outputs, etc.

The 8-core i7 5960x ran about 30,000 on 64-bit Geekbench; the 6-core i7 5820K was around 22,500. The 4-core i7 4790K ran around 16,500 - maybe even 17,000. All processors were running at 4GHz. Then, when I ran the constant-loop Geekbench stress test mode (which I believe only runs in 32-bit mode), the scores were about 29,000 22,000 and 15,500 respectively (due to the 32-bit mode). HOWEVER, after about 5-10 minutes (maybe even less) the 4790K throttled down to 13,500 and wouldn't go any higher. The 6 and 8 core processors maintained their speed for hours on end.

I was originally excited about the prospect of running the "high-value" 4790K processor, but after realizing it barely ran faster than my $600 i7 laptop under load (which can't always handle video streaming without stuttering, even though GB stress test remains steady on it at 11,500 for 30+ minutes), I took it back and kept the 6 and 8 core machines. And I've had zero stuttering problems with them.

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Thanks for bringing this up. This is very true, and now I'm starting to remember why I got the Mac Pro to begin with.

1) Get the extra cash
2) Get a 5K retina display (although I currently use 4K. I know. I'm ridiculous)
3) To do videos about the 5K iMac (I have a fairly large YouTube channel & Web site that I do as my full-time job writing about, and doing videos on, tech)
4) The most I do with the Mac Pro is use FCPX to edit 1080p video, and I feel like there's a lot of wasted power here after reading the Marco Arment article on Mac Pro vs iMac 5K

So, all that said, after using the Mac Pro and not really needing it as much for work, I thought I'd get as much as I can for it now while there is still 3 more months of the 1-year Apple warranty on it than wait until later.

1) Get the extra cash
2) Get a 5K retina display (although I currently use 4K. I know. I'm ridiculous)
3) To do videos about the 5K iMac (I have a fairly large YouTube channel & Web site that I do as my full-time job writing about, and doing videos on, tech)
4) The most I do with the Mac Pro is use FCPX to edit 1080p video, and I feel like there's a lot of wasted power here after reading the Marco Arment article on Mac Pro vs iMac 5K

So, all that said, after using the Mac Pro and not really needing it as much for work, I thought I'd get as much as I can for it now while there is still 3 more months of the 1-year Apple warranty on it than wait until later.

So here is the same as you have http://www.ebay.com/itm/Mac-Pro-3-5...7145718?pt=Apple_Desktops&hash=item3a9887e3f6 (I think). Subtract all the fees you are looking at 4700 through eBay. Craigslist would be the best as it will be cash and no fees, however, depending on where you live that might be a hard sell. Outside of that, I don't really know where you could sell one. They are selling pretty fast on eBay, so there is definitely a market for it.

I think this one undersold a bit too much. I'd go for $6k if possible. But like I said, craigslist, friends, etc, would be better. Facebook, just anything you can think of.

So here is the same as you have http://www.ebay.com/itm/Mac-Pro-3-5...7145718?pt=Apple_Desktops&hash=item3a9887e3f6 (I think). Subtract all the fees you are looking at 4700 through eBay. Craigslist would be the best as it will be cash and no fees, however, depending on where you live that might be a hard sell. Outside of that, I don't really know where you could sell one. They are selling pretty fast on eBay, so there is definitely a market for it.

I think this one undersold a bit too much. I'd go for $6k if possible. But like I said, craigslist, friends, etc, would be better. Facebook, just anything you can think of.

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Thank you - the one you linked is similar to mine, with the exception of the RAM (mine is 64GB rather than 32GB) - but it is a good starting point. I've had it listed on CL since the day Apple announced the new iMac, but not one email...seems Craigslist isn't the place for super high-end stuff like that. I'll probably throw it on eBay today, although that also makes me wary because a buyer can just say they didn't receive it or say they got an empty box, and eBay refunds them with almost no questions asked!

Thank you - the one you linked is similar to mine, with the exception of the RAM (mine is 64GB rather than 32GB) - but it is a good starting point. I've had it listed on CL since the day Apple announced the new iMac, but not one email...seems Craigslist isn't the place for super high-end stuff like that. I'll probably throw it on eBay today, although that also makes me wary because a buyer can just say they didn't receive it or say they got an empty box, and eBay refunds them with almost no questions asked!

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Always always make sure you ship to confirmed address only. No exceptions. Also, require signature for delivery. When you receive payment, paypal should show a green checkmark next to the person's name which verifies that it's a real address as well a confirmed address. This will protect you the most.

I've sold very expensive stuff on eBay before. As long as you cover your ass in every way possible, it's not too bad minus the fees of course.

By the way, I have 3.5 6-core, 32gb, 1TB SSD. I will do a buy it now for 4800. So you get an idea for price. I will also offer local pickup in eBay.

Always always make sure you ship to confirmed address only. No exceptions. Also, require signature for delivery. When you receive payment, paypal should show a green checkmark next to the person's name which verifies that it's a real address as well a confirmed address. This will protect you the most.

I've sold very expensive stuff on eBay before. As long as you cover your ass in every way possible, it's not too bad minus the fees of course.

By the way, I have 3.5 6-core, 32gb, 1TB SSD. I will do a buy it now for 4800. So you get an idea for price. I will also offer local pickup in eBay.

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I appreciate that advice. For local pickup, how do you prove that it happened?

I appreciate that advice. For local pickup, how do you prove that it happened?

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Not sure how that works. I always offered it, but no one ever picked up. Not sure honestly. Maybe don't do it then, unless it's craigslist. I mean keep in mind, you can always chat with the people. If it's local pickup, give them 100 discount if they are willing to pay cash. It's a hell lot cheaper than paying eBay fees. And in person, cash, is always better. Just be sure to kill the auction before it takes place, so that 1) you don't pay fees, and 2) you can't be flagged even though the person already picked it up.

But don't accept paypal, cashiers check, any of that s*** unless there is a signature for the shipment.

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